It is known that electronic modules, for example electronic modules having a DC-DC converter, generate waste heat as a result of electrical losses and, for this reason, are connected to one or more heat sinks in order to dissipate the waste heat formed.
Furthermore, it is already known practice to provide electronic devices either in an open configuration or to install said devices in a housing. Such electronic devices tend to have a problematic EMC behavior, that is to say increased radio-frequency emissions.
If the electronic device contains a DC-DC converter, the steep rising and falling edges produced therein of the currents and voltages flowing through the parts of the DC-DC converter cause radio-frequency electromagnetic fields. As a result of the open configuration or else as a result of housing walls made of dielectric materials, said fields pass to the area surrounding the electronic device, which corresponds to the presence of undesirable emissions.
There are already industrial standards which define limit values for such emissions as well as relevant measuring methods. These standards include, for example, DIN EN 55022 for industry and IEC CISPR 25 for the automotive sector.
Complying with these standards, in particular in the automotive sector, is generally a demanding challenge which is generally associated with considerable time and costs for the respective manufacturer.
In this connection, it is already known practice to arrange an electronic module which generates radio-frequency electromagnetic fields in a housing made of electrically conductive material, the components of which are electrically connected to one another. As a result, a large part of the interference fields generated by the electronic module inside the housing is intercepted by the walls of the housing and is possibly discharged to ground. This is effected in most cases using an AC path which is provided for this purpose and, starting from the electronics, extends, through the air, to the housing and from the latter, via capacitors or via a direct electrical connection, to printed circuit board ground and from there, via a cable harness, into the negative pole of the automobile battery or the vehicle electrical system of a motor vehicle.
In practice, this is often achieved by means of a pre-punched component which is arranged above the emitting components and is made of electrically conductive material. This component can be fastened by means of soldering or by means of a pressing-in operation. When establishing the mechanical connection, care is taken to ensure that the best possible electrical connection to a defined potential, usually ground, is also produced. This electrical connection then forms a path for the currents which induce the interference fields in the component in the form of a shield.
Alternatively, it is possible to use a two-part housing having a lower part and an upper part, the upper part being able to be a sheet metal lid. In the case of such an implementation, a printed circuit board, for example, on which the emitting electronic components are provided is connected to the lower part by means of screws. These screws provide mechanical support and ensure an electrical connection between printed circuit board ground and the housing. The upper part is typically screwed on or is mechanically fastened to claws, tongues or springs with the aid of a spring construction or by means of latching apparatuses and is also electrically connected to the lower part. This produces a construction which is more or less closed in terms of EMC and, with a correct design, approximates a Faraday cage.